The m5zn.6xlarge is a general-purpose AWS EC2 instance: 24 vCPU and 96 GiB of memory, 4.00 GiB per vCPU. In the name, "m" is the general-purpose line, "5" is the generation, "zn" marks a higher clock and enhanced networking and "6xlarge" is the size within the m5zn family. It runs on Intel Xeon Platinum 8252 at 4.5 GHz, and AWS introduced it in December 2020. AWS has since shipped m6i, m7i, m8i and m9g; m8azn.6xlarge is the direct replacement at this size. No single Spot node covers 24 vCPU and 96 GiB, so the equivalent is a fleet: 2 × gp.vs1.2xlarge, 32 vCPU and 128 GiB in total, $1.98/hr on AWS in US East (N. Virginia), from $0.082/hr on Rackspace Spot. Spot delivers compute as managed Kubernetes, so a node pool of that size is the native shape of the answer rather than a workaround — provided the workload scales horizontally.
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m5zn.6xlarge gives you 24 vCPU and 96 GiB in a single machine. The largest comparable Spot node, gp.vs1.2xlarge, is 16 vCPU and 64 GiB, so the equivalent here is 2 nodes rather than one.
Spot runs as managed Kubernetes, so a 2-node pool is the normal way to run things rather than a workaround. If your workload already sits behind a load balancer, a queue or a scheduler, it spreads across them without changes. If it needs all 24 cores and 96 GiB in one process, it does not.